UVB-76

UVB-76, also known as '"the Buzzer", is the nickname given by radio listeners to a shortwave radio station that broadcasts on the frequency 4625 kHz. It broadcasts a short, monotonous  buzz tone , repeating at a rate of approximately 25 tones per minute, for 24 hours per day. Sometimes, the buzzer signal is interrupted and a voice transmission in Russian takes place. The first reports were made of a station on this frequency in 1982. Its origins have been traced to Russia, and although several theories with varying degrees of plausibility exist, its actual purpose has never been officially confirmed and remains a source of speculation.

The name

The station is commonly known as the Buzzer in both English and Russian (жужжалка žužžalka). Its official name is not known, although some of the voice transmissions have revealed names which may be callsigns or another form of identification. Up until September 2010, the station identified itself as UVB-76 (Cyrillic: УВБ-76), and it is still often referred to by that name. In September 2010, the station moved to another location, and it has used the identification MDZhB (Cyrillic: МДЖБ, Russian phonetic spelling "Mikhail Dmitri Zhenya Boris") from then onwards. It is possible that the correct identification until September 2010 was actually UZB-76 (Cyrillic: УЗБ-76), and that the Cyrillic letter Ze (З) had been misheard as the letter Ve (В). However, it is still referred to as "UVB-76" by most people. Although the station, by and large, has used these two codes at the beginning of most voice transmissions, a few voice messages have used other identification codes. This makes it uncertain whether the names are actually the callsign of the station, or some other identifying code. Now this radio have a name "ZhUOZ".

Ultraviolet

Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 400 nm (750 THz) to 10 nm (30 PHz), shorter than that of visible light but longer than X-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310 nm, and people with aphakia (missing lens) can also see some UV wavelengths. Near-UV is visible to some insects and birds.

UV radiation is present in sunlight, and also produced by electric arcs and specialized lights such as mercury-vapor lamps, tanning lamps, and black lights. Although lacking the energy to ionize atoms, long-wavelength ultraviolet radiation can cause chemical reactions, and causes many substances to glow or fluoresce. Consequently, biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.

Suntan, freckling and sunburn are familiar effects of over-exposure, along with higher risk of skin cancer. Living things on dry land would be severely damaged by ultraviolet radiation from the sun if most of it were not filtered out by the Earth's atmosphere, particularly the ozone layer. More-energetic, shorter-wavelength "extreme" UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground. Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has effects both beneficial and harmful to human health.